Hydrodynamic cavitation is widely known as a method used to obtain free disperse systems, particularly lyosols, diluted suspensions, and emulsions. Such free disperse systems are fluidic systems wherein dispersed phase particles have no contacts, participate in random beat motion, and freely move by gravity. Such dispersion and emulsification effects are accomplished within the fluid flow due to cavitation effects produced by a change in geometry of the fluid flow.
Hydrodynamic cavitation is the formation of cavities and cavitation bubbles filled with a vapor-gas mixture inside the fluid flow or at the boundary of the baffle body resulting from a local pressure drop in the fluid. If during the process of movement of the fluid the pressure at some point decreases to a magnitude under which the fluid reaches a boiling point for this pressure, then a great number of vapor-filled cavities and bubbles are formed. Insofar as the vapor-filled bubbles and cavities move together with the fluid flow, these bubbles and cavities may move into an elevated pressure zone. Where these bubbles and cavities enter a zone having increased pressure, vapor condensation takes place within the cavities and bubbles, almost instantaneously, causing the cavities and bubbles to collapse, creating very large pressure impulses. The magnitude of the pressure impulses within the collapsing cavities and bubbles may reach 150,000 pounds per square inch. The result of these high-pressure implosions is the formation of shock waves that emanate from the point of each collapsed bubble. Such high-impact loads result in the breakup of any medium found near the collapsing bubbles.
A dispersion process takes place when, during cavitation, the collapse of a cavitation bubble near the boundary of the phase separation of a solid particle suspended in a liquid results in the breakup of the suspension particle. An emulsification and homogenization process takes place when, during cavitation, the collapse of a cavitation bubble near the boundary of the phase separation of a liquid suspended or mixed with another liquid results in the breakup of drops of the disperse phase. Thus, the use of kinetic energy from collapsing cavitation bubbles and cavities, produced by hydrodynamic means, can be used for various mixing, emulsifying, homogenizing, and dispersing processes. These processes typically generate heat and require cooling systems to prevent or reduce thermal related damage to the devices, seals and other components, the reactants, and the reaction products.
Devices are known in the art which utilize the passage of a hydrodynamic flow through a cylindrical flow-through chamber internally accommodating a baffle body installed across and confronting the direction of the hydrodynamic flow to produce varied cavitations effects. The baffle element provides a local contraction of the flow as the fluid flow confronts the baffle element thus increasing the fluid flow pressure. As the fluid flow passes the baffle element, the fluid flow enters a zone of decreased pressure downstream of the baffle element thereby creating a hydrodynamic cavitation field. One such device is described in U.S. Pat. No. 5,492,654, which is totally incorporated by reference herein. Further patents of interest include U.S. Pat. Nos. 5,417,956, 6,365,555, 6,589,501, 5,810,052, 5,937,906, 6,502,979, and 6,802,639, the disclosures of each of which are totally incorporated by reference herein.
Various cooling devices and methods are known for cooling reactions. Such cooling devices are required to avoid or minimize heat damage to the reaction products, the reaction devices, or both. Reference, for example, U.S. Pat. Nos. 5,143,515, 4,842,055, 4,646,822, 4,601,040, 4,600,052, 4,249,595, 4,247,262, and 4,212,594, the disclosures of each of which are totally incorporated herein.
The disclosures of each of the foregoing U.S. Patents are each totally incorporated by reference herein in their entireties. The appropriate components and process aspects of the each of the foregoing U.S. Patents may be selected for the present invention in embodiments thereof.
A known device 10 for cooling a cavitation device 12 is shown in FIG. 1 (in order to focus on the cooling method, a portion of a representative cavitation device 12 is shown; elements of the cavitation device 12 not related to the cooling system 10 are not shown in FIG. 1). The representative cavitation device 12 includes a flow-through channel 14 for passing a fluid, indicated as arrow 16, such as a mixture of reaction components, such as a liquid and dispersants, such as, for example, a charge transport layer dispersion. The flow 16 of the liquid and dispersants enters the flow-through channel 14 through an inlet (not shown) in a first end 32 of the flow-through channel 14 moving in the direction of the arrow 16 and exiting through an outlet (not shown) in a second end 36 of the flow-through channel 14. A plunger 18 slidably movable coaxially within the flow through chamber to effect the creation and control of cavitation fields is disposed at least partially within the flow-through channel 14. The plunger 18 is surrounded by a sealed solvent jacket 20 which includes a solvent housing 22 for containing a cooling solvent 24, a solvent inlet 26 and a solvent outlet 28. The solvent jacket 20 includes a regular or low pressure seal 30 at the first end 32 of the flow-through channel 14 and a high pressure seal 34 at the second opposite end 36 of the flow-through channel 14. Without cooling, the seals are heated up and eventually melt. It has been proposed to pass the solvent 24 through a solvent refrigeration loop (refrigeration device not shown) to cool the plunger seals while also employing a separate water loop to cool the solvent.
There remains a need for a cooling device and method for cavitation type devices that is less costly and less complicated than currently available devices. There is further a need for a device and method for cooling and lubricating such devices without contamination of seals, other parts, and reaction or dispersant materials due to seal damage from over heating.